1. Field of the Invention
The present invention relates to materials for the manufacture of nonwoven tissues having particular softness and strength. The nonwoven material segment of the overall wiper market has grown due to the economy of such products, as well as the ability to tailor the wipers for specific applications. For example, nonwoven wipers are available having absorbency properties particularly suited for oil wiping, for food service wiping and for wiping of high technology electronic parts. Such nonwoven materials may be manufactured by a number of known processes, including wet-forming, air-forming and extrusion of thermoplastic fibers. The present invention is related to an improvement in nonwoven facial tissues formed using a meltblowing process to produce microfibers, incorporating particular cellulosic fibers having utility and diverse applications and particularly unique softness.
2. Description of the Pertinent Art
U.S. Pat. No. 4,426,417 discloses a wiper comprising a matrix of nonwoven fibers having a basis weight of 25 to 300 gsm including a meltblown web holding a staple fiber mixture therein. The matrix contains up to 90% fiber blend of which 90% is synthetic fibers.
Meltblown nonwoven microfiber materials are known and have been described in a number of U.S. Patents, including U.S. Pat. No. 4,328,279 to Meitner and Englebert, U.S. Pat. No. 4,298,649 to Meitner and U.S. Pat. No. 4,307,143 to Meitner. The preparation of thermoplastic microfiber webs is also known and described, for example, in Went, Industrial and Engineering Chemistry, Volume 48, No. 8 (1956), pages 1342 through 1346, as well as in U.S. Pat. Nos. 3,978,185 to Buntin, et al., 3,795,571 to Prentice and 3,811,957 to Buntin. These processes generally involve forming a low viscosity thermoplastic polymer melt and extruding filaments into a converging air stream which draws the filaments to fine diameters on the average of up to about 10 microns, which are then collected to form a nonwoven web. The addition of pulp to the air stream to incorporate the pulp into the meltblown fiber web is also known and described in U.S. Pat. No. 4,100,324 to Anderson, Sokolowski and Ostermeier.
While tissues produced in accordance with the disclosures of these patents have, in some cases, achieved good acceptance for a number of wiping applications, it remains desired to produce a nonwoven facial tissue having extremely high softness while maintaining good wiping properties, i.e., the ability to wipe quickly and having good strength. It is desired to produce such a facial tissue at a cost consistent with disposability and having strength properties for rigorous wiping applications. Wipers of the present invention attain to a high degree these desired attributes.